Filling in the Blanks, a guide to generating lairs and features for hexcrawl-style games (or anytime you need wilderness encounters) is live on Drivethrurpg with hard and softcover options in addition to pdf. While written for OSR-style games (Old School Essentials in particular), it can be used for any fantasy-style game.
Filling in the Blanks - Third Kingdom Games | DriveThruRPG.com
Filling in the Blanks - Third Kingdom Games | DriveThruRPG.com